In known general internal gear shaving machines as disclosed in, for example, Japanese Unexamined Patent Publication No. 2003-117729, an internal gear rotatably supported around a horizontal axis by a workpiece chuck engages a shaving cutter at a predetermined crossed axes angle, and the tooth flanks of the internal gear are finished while at least one of the shaving cutter and the workpiece chuck is rotationally driven.
However, in such a known internal gear shaving machine, shavings produced during shaving disadvantageously remain on the internal teeth of the internal gear and adversely affect the processing accuracy. Moreover, there is a problem of the difficulty in changing the workpiece and the engagement (phasing) of the shaving cutter and the internal gear in changing workpieces.